Mechanical stoker



May 13, 1930. w. M. DUNCAN 1,758,075

MECHANICAL STOKER Filed July 8, 1925 2 Sheets-Sheet l l/YVE/yroR IM .50h/74N Bv Arran/vins Patented May 13, 1930 UNITED STATES PATENT OFFICE MECHANICAL STOKER Application iled July 8,

This invention relates to mechanical stokers, and more particularly to a stoker wherein an endless traveling chain grate passes around supporting members at the front and rear of the grate structure. One of the objects is to produce a st-rong and durable support for a stoker of this kind, and this feature can be used most advantageously in a wide stoker driven by rotary members surrounded by and forming supports for a very heavy grate structure. A further object is to provide a strong and simple rotary support on which the chain grate structure is turned to discharge the ashes.

Another object is to produce a double stoker wherein a pair of endless chain grates are arranged alongside of each other with their top faces in substantially the same plane, so as to support a wide bed of fuel in a arge combustion chamber. The two separate grates, operating substantially as a single unit, are stronger than a large wide grate, for the supports merely require the strength necessary to support relatively small grates, and it is not necessary to transmit the driving stresses through a very long drive shaft.

With the foregoing and other objects in view, the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawing, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention comprehends changes, variations and modifications which come within the scope of the claim hereunto appended.

Fig. I is a longitudinal section showing the lower portion of a furnace equipped with a mechanical Stoker embodying the features of this invention.

Fig. II is a transverse section taken approximately on the line II-II in Fig. I.

Fig. III is a perspective View of the adjustable bearing for the inner ends of the drive shafts.

Fig. IV is a perspective view of another of the adjustable bearings.

Fig. V is a horizontal section taken approx- 50 imately on the line V--V in Fig. I, with out- Serial No. 42,149.

lines of the chain grates indicated by dot and dash lines.

The furnace shown in Figs. I and II comprises side walls l, a wall 2 at the rear of the grate and a fuel hopper 3 above the front portion of the grate.

The mechanical stoker includes side frames 4- below the side walls l, a stationary separating plate 5 arranged parallel with and approximately midway between the side frames 4t, and a pair of endless chain grates A, the separating plate 5 being located between the grates. The inner sides of the grates are adjacent to each other, and their outer sides lie adjacent to the side frames. Each chain grate comprises numerous grate links 6 pivotally connected to ether at 7, as shown most clearly in Fig. The top faces ofthe two grates lie in the same horizontal plane and they form the bottom of a single combustion chamber. The top of the separating plate 5 is lower than the top of the grate surace.

The means for supporting the grates includes side bearingsS (Figs. II, IV and V) slidably mounted in the side frames 4;, and an intermediate bearing 9 slidable in the separating plate 5. Two rotary drive shafts l0 are mounted in the bearings 8 and 9. These shafts are in alinement with each other and their adjacent inner ends lie in the bearing 9, as shown by Figs. II and V. Their outer end portions extend through the bearings 8 to receive any suitable operating means (not shown). Each shaft 10 is surrounded by one of the grates and provided with sprocket wheels l1 adapted to engage the surrounding grate. The two grates are thus driven by relatively short shafts l0 adapted to be operated independently of each other, and each shaft supports the front portion of one of the surrounding grates. The shafts are driven at approximately the same speed, but it would be both difficult and expensive to use a driving mechanism that would operate them at exactly the same speed. The separating plate 5 is utilized to prevent one grate from coming into actual Contact with the other, for the traveling grates have irregular side faces and since they may travel at slightly ydifferent speeds, such Contact would be likely to cause breakage or other injury to the structure.

12 designates rotary supporting members surrounded by the respective grates and located at the rear portions thereof to provide cylindric faces on which the grates are turned to discharge the ashes. These members 12 are preferably in the form of cylindrical tubes having journals 13 extending from their ends and mounted in bearings 14 and 15, the bearings 14 being in the side frames 4 and the bearing 15 being in the separating plate, or partition, 5. The journals 13 extend from circular blocks 16 in the end portions of the tubes. The rotary tubes 12 are arranged in longitudinal alinement and their inner ends lie adjacent to each other, but the separating member 5 lies between the tubes, so they are entirely free to rotate independently of each other. These relatively short tubes supported in bearings at their ends provide strong and simple support-s for the double grate.

The slidable bearings 8 and 9 are adjustable to tighten the chain grates. Threaded rods 18 (Figs. II, IV and V) are secured to each bearing 8 as shown most clearly in Fig. IV, and each of these rods extends through a lug 19 projecting from one of the side frames, as shown in Fig. V, to receive an adjusting nut 20. In adjusting the outer ends of shafts 10, the nuts 2O are turned to shift thebearings 8.

The means for adjusting the inner ends of the shafts 10 comprises pull rods 21 (Figs. I, III and V) extending from the bearing 9 and having threaded outer ends which pass through a plate 22 to receive adjusting nuts 23. rIhese nuts can be adjusted to pull the rods 21 and thereby shift the slidable bearing 9. The inner ends of the shafts 10 which are surrounded by the grate structure can be thus adjusted through the medium of operating rods 21 which pass between the adjacent side faces of the traveling grates A, so as to receive an adjusting member entirely outside of the grate structure.

The grate travels in the direction indicated by arrows in Fig. I to receive the fuel from hopper 3 and discharge the ashes at the rear of the rotary tubes 12.

A forced draft may be supplied through pipes 24 (Fig. V) leading to passageways 25 communicating with openings 26 in the side frames 4. The partition, or separating member 5, is provided with openings 27 (Figs. I and V) for the purpose of equalizing the draft pressure within the double grate structure. To prevent escape of draft through the ends of the grates, each grate is provided with a front wall 28 and a rear wall 29 (Figs. I and V) and the draft can be regulated by means of movable dampers 30 cooperating with stationary plates 31. The members 28, 29, 30 and 31 are supported by beams 32 arranged transversely of the grates. The upper portions of t-he grates travel on bars 33 and 34 supported by the beams 32. The lower portions of the grates are supported by tracks 35, shown in Figs. I and II.

36 designates elongated plates (Figs. I and V) resting on the lower portions of the traveling grates and having upturned ends at the front and rear adapted to engage stationary tubes 37. These plates 3G are provided vvit-h numerous openings 38 for the discharge of ashes and other fine material that fall through the fuel-supporting portions of the grates. This material enters into the lower portions of the traveling grates and it is discharged when the grate links turn on their pivots in passing around the drive wheels 11.

I claim:

A double stoker comprising a pair of endless traveling` chain grates, separating means interposed between the adjacent sides of said grates, rotary driving means including a pair of drive shafts surrounded by said grates and forn'iing supports therefor, and adjusting means whereby said driving means is shifted to tighten the chain grates, said adjusting means including a bearing surrounded by the grate structure and forming a support for both of said shafts, an adjusting member at the exterior of the grate structure and a connection device passing between the adjacent sides of the grates and extending from said bearing to said adjust-ing member, so as to connect the bearing to the adjusting member.

In testimony that I claim the foregoing I hereunto a'liX my signature.

IVILLIAM M. DUNCAN. 

